a. Field of Invention
This invention pertains to a machine for drilling holes in rocks, and more particularly, for drilling relatively wide, yet shallow, holes suited for installation of utility poles, street lighting, guard railing, highway sound barriers, etc.
b. Description of the Prior Art
Utility poles are widely used for stringing various cables and wires in open country, which cables carry electric power, telephone signals and so forth. Several poles must be positioned in straight lines along preselected routes and rights-of-way, at preselected positions and spacings dependent on the weight of the cables, weather conditions in the area, etc. Thus, the pole positions are not dictated by, and in most instances cannot be changed to suit, local geological conditions. Thus, if soil at a particular pole position consists of a mass of rock, a hole must be dug in the rock for the pole. Until now, such holes could be made by either core drilling or blasting. Core drilling is very slow. A hole in a typical rock mass may take up to half-a-day. Blasting is quicker, but also very dangerous resulting in irregular holes which must be shaped by filler material, such as cementor run a crush, before they can be used for positioning poles.
Other equipment is available for digging holes in rock for other purposes. For example, the Buckeye Drill Company of South Milwaukee, Wis., makes a rotary drill machine Model No, 2400-R which can be used to make holes of 6-30 inches in diameter to a depth of 2500 feet for oil or water. However, this equipment weighs 61,000 pounds and, therefore, is difficult to transport to remote locations, especially if no roads are found nearby. Furthermore, this equipment is expensive to buy and to operate.
Another available machine is from Gemco Equipment Co., Houston, Tex., which is used for geological and seismographic surveys. However, this machine is capable of making only 4 inch holes. Furthermore, this machine is not only extremely heavy, but also large and cumbersome, so that it is not well suited for transportation through narrow areas or embankments.
Thus, there exists a need for a special type drilling machine for making holes in rocks for utility poles, street lighting, guard railing, highway sound barrier, etc.